Apparatus for use in diffusion transfer copying

ABSTRACT

A COPYING APPARATUS FOR USE IN SILVER COMPLEX DIFFUSION TRANSFER COPYING THE LIKE WHEREIN THE LEADING EDGES OF SHEET MATERIAL PROCESSED WITHIN SUCH APPARATUS ARE PRECISELY ADJUSTED RELATIVE TO ONE ANOTHER IN A VARIABLE OR ADJUSTABLE WAY. THE SHEETS ARE SEPARATELY FED BY SEPARATE INDEPENDENTLY OPERABLE FEEDING ROLLS, THE FEEDING OF WHICH IS STOPPED WHEN THE LEADING EDGE OF EACH SHEET REACHED A SENSING MEANS DISPOSED AT A PREDETERMINED POINT BETWEEN THE FEEDING ROLLS AND THE PROCESSING ZONE. THE SENSING MEANS FOR THE SECOND SHEET REINITIATES THE FEEDING OF THE FIRST SHEET AND ACTIVATES A TIME-DELAY DEVICE WHICH, AFTER A VARIABLE PRE-SET PERIOD OF DELAY, REINITIATES THE FEEDING OF THE SECOND SHEET SO THAT THE SHEETS ARRIVE AT THE PROCESSING ZONE WITH THEIR LEADING EDGES IN PRECISELY DETERMINED, SPACED-APART RELATION WHICH CAN BE ADJUSTED AS DESIRED.

1 R. sumom ETAL APPARATUS FOR USE IN DIFFUSION TRANSFER COPYING mm: Mai-ch 17. 1969 4 Sheqt s-Sheet 1 R. smuom ETAL 3,616,741

4 Sheets-Sheet 2 Nov. 2, 1971' APPAR'ATus FOR USE IN DIFFUSION TRANSFER COPYING Filed March 17. 19691 \mm a NM 2 2 2 2 ||l 1 u H l e v Mw M W a z 3 w H \NR v w 5 r wm lm 3 W2 v .H Q B Nov. 2, 1911 Y R.s|Ml0N| ETAL 3,616,741

I APPARATUS FOR USE IN DIFFUSION TRANSFER COPYING Nov. 2, 1971 R. SIMIONI ErAL 3,616,141 APPARATUS FOR USE n nmpusxon mumsma cornue Filed March 17, 1959 v -4 Sheets-Sheet 4 FIG. 5

United States Patent Ofice 3,616,741 Patented Nov. 2 1971 US. 7 Claims ABSTRACT OF THE DISCLOSURE A copying apparatus for use in silver complex diffusion transfer copying and the like wherein the leading edges of sheet material processed within such apparatus are precisely adjusted relative to one another in a variable or adjustable way. The sheets are separately fed by separate independently operable feeding rolls, the feeding of which is stopped when the leading edge of each sheet reaches a sensing means disposed at a predetermined point between the feeding rolls and the processing zone. The sensing means for the second sheet reinitiates the feeding of the first sheet and activates a time-delay device which, after a variable pre-set period of delay, reinitiates the feeding of the second sheet so that the sheets arrive at the processing zone with their leading edges in precisely determined, spaced-apart relation which can be adjusted as desired.

The present invention relates to apparatus for use in copying documents by the silver complex diffusion transfer process.

In the performance of the silver complex diffusion transfer process an image-wise exposed light-sensitive sheet, normally a sheet comprising a silver halide emulsion layer (hereinafter called the light-sensitive sheet), 7

is treated with a processing liquid to bring about development of the latent image and is pressed against a sheet material (hereinafter called the receiving sheet) to which complexed silver halide diffuses from the lightsensitive material and is transformed to form another image of the printed text or other matter which is being copied.

If an exact predetermined positioning of the image on the receiving sheet is required, it is necessary to ensure a correct predetermined relative location of the lightsensitive sheet on the receiving sheet during the diffusion transfer.

The subject of the present invention is apparatus having means for enabling such correct relative-positioning of the sheets. More particularly, the invention aims at providing apparatus which allows the relative positioning of the sheets to be finely adjusted, especially in the longitudinal direction, i.e. the direction of travel of the sheets through the apparatus.

The invention is particularly although not exclusively concerned with the performance of the diffusion transfer process using a receiving sheet which can subsequently be used in offset printing, e.g. a receiving sheet comprising a metal support such as an aluminium foil.

Apparatus for use in carrying out the diffusion transfer process are known, which have means for relatively positiming both sheets prior to their guidance into the processing bath. In such apparatus, the positioning of the sheets in the transverse direction is accomplished by means of side guide members. The positioning of the sheets in the longitudinal direction, however, mostly requires a high level of precision by the operator in order to obtain reproducible results and, moreover, the known systems for enabling the longitudinal positioning of the sheets do not permit an easy modification of said positioning.

According to the present invention, an apparatus for use in copying by the silver complex diffusion transfer process, comprises first guide means for guiding a lightsensitive sheet along a determined path extending through a processing zone, second guide means for guiding a receiving sheet along a determined path so that this sheet is spaced from said light-sensitive sheet, sheet-pressing and sheet-driving means arranged at the exit end of said zone for pressing said two sheets together and for removing them from the apparatus, and sheet-aligning means, comprising a first and a second pair of driving rollers at the entry end of the processing zone for driving said sheets separately towards said first and second guide means, lateral guide means for determining the lateral position of the sheets before they are engaged by said pairs of driving rollers, and first and second sensing means which are responsive to the arrival of the leading edges of the sheets at a determined locus on their paths between said pairs of driving rollers and said processing zone and which control the rotation of said driving roller pairs, the first sensing means causing at the detection of the leading edge of a sheet the arresting of the rotation of the pair of rollers advancing said sheet, the second sensing means causing at the detection of the leading edge of the other sheet the arresting of the rotation of the pair of rollers advancing said sheet and, at the same moment, re-starting the rotation of the pair of rollers engaging said one sheet and starting also a time delay mechanism, said time delay mechanism restarting after a preset time the rotation of the pair of rollers engaging said other sheet so as to continue the advance of the sheet gripped thereby at least until said sheet is urged against the other sheet by said pressing means.

According to a preferred embodiment, the time delay mechanism comprises a rotatable shaft which may be coupled through a magnetic clutch to an electric motor which is continuously running during the operation of the apparatus, said rotatable shaft being composed of a first, hollow shaft portion which carries the said magnetic clutch and a first cam, and a second shaft portion passing axially through the first one, one end of said second shaft portion extending out of the apparatus and carrying a knob which provides with a stationary dial an indication in the desired mutual distance between the leading edges of the sheets, the opposite end of said shaft carrying a second cam, and a slip clutch through which said first and second shaft portions are coupled to each other and which permits the operator to angularly displace one shaft portion in respect of the other. The first cam actuates a microswitch which controls the part of an electric circuit which makes the shaft effect one complete revolution each time, whereas the second cam actuates a microswitch which controls the re-starting of the rotation of the pair of driving rollers engaging the said other sheet.

The processing zone of the apparatus will mostly comprise a tray holding a body of liquid for developing the silver halide and for solving the non-exposed parts of the light-sensitive layer of the light-sensitive sheet as this sheet is guided by the guide means through the body of liquid in the tray. The guide means for the receiving. sheet may provide for the guidance of said sheet also through said body of liquid. The invention will now be described by way of an example with reference to the accompanyin drawings, wherein:

FIG. 1 is a perspective view of the apparatus accordin to the invention.

FIG. 2 is a diagrammatic longitudinal section of the apparatus.

FIG. 3 shows the driving of the rotating parts of the apparatus.

FIG. 4 is a diagrammatic front view of the time delay mechanism.

FIG. 5 is the electric circuit of the apparatus.

The apparatus shown in FIGS. 1 and 2 comprises a housing wherein the processing zone and the sheetaligning, the sheet-driving and the sheet-pressing means are located, and a feed-unit 11 which facilitates the feeding of an image-wise exposed light-sensitive sheet 12 and an aluminium receiving sheet 13 into the apparatus.

The feed-unit 11 comprises two horizontal support plates 14 and 15 which may be fitted to the housing 10 by means of triangular brackets 16 which are provided with hooks 17 and 18 which fit at each lateral side of the apparatus over studs 19 and 20. The upper support plate 14 is hingedly connected to the feed unit by means of hinges 21, 22. In the closed position, as shown, the plate 14 rests with its front margin on the support blocks 23, 24 fitted to the lower support plate 15. The upper support plate 14 carries a guide 25 which defines the lateral position of the sheet 12. The guide is continuously laterally adjustable by means of a mechanism sliding in the slot 26 and which may be locked by the locking knob 27. The lower support plate 15 has a guide 28 which defines the lateral position of the sheet 13. The said guide has two possible positions, the second being shown in broken lines, and is secured to the plate by means of a snap-fitting mechanism, not shown.

The processing zone in the housing 10 is formed by a plate 30 shaped as shown, which is supported by a frame 36. Processing liquid is pumped to the tray from a reservoir 31 by a pump 32-. The inlet 33 of the tray is located near one lateral side thereof, whereas the outlet is formed by an overflow pipe 34 which is located in the tray near the opposite lateral side and which fits to the plate 30 except for a small opening 37. The interior of pipe 34 communicates through opening 38 with a conduct 39 which leads to the reservoir 31. In the operation of the apparatus, the duty of the pump 32 is slightly greater than the quantum of liquid which flows through the opening 37. After starting the apparatus the level of the processing liquid in the tray rises until the level 35, determined by the upper edge of pipe 34, is reached. At that moment the surplus of liquid is carried off through pipe 34 and conduct 39 to the reservoir 31.

The plate 30 is provided with laterally spaced ribs 40 which determine the path of the sheet 13 through the processing liquid. Guide plates 41 and 42 which are provided above the plate 30, determine the path of the sheet 12 through the processing zone. The plates 41 and 42 are provided with a plurality of openings, not shown, for enabling the circulation of the processing liquid.

The driving of the sheets through the apparatus occurs by means of the roller pairs 43, 44, and 45, 46 which feed the sheet 12 and the sheet 13- respectively, through the processing zone, and by the roller pair 47, 48 which presses the sheets firmly together as they leave the processing zone. During the operation of the apparatus the roller pair 47, 48 is continuously rotating whereas the rotation of the roller pairs 43, 44 and 45, 46 is controlled 4 by sensing devices which are responsive to the arrival of the leading edge of the sheets at a determined locus.

A first sensing device comprises a microswitch 92 7 (FIG. 3) which is controlled by a rotatable rod 49 extending transversally of the apparatus and carrying one or more fingers 50 formed by a steel wire tightly wound with a few spires around the rod and intercepting with a free extremity the path of a sheet advanced by the roller pair 45, 46. A second sensing device comprises a microswitch 93 which is controlled in a similar way by a rotatable rod 51 carrying finger 52.

The driving mechanism of the apparatus and the parts operative in the sheet-aligning are illustrated in detail in FIG. 3 wherein for the sake of clearness the geometric disposition of a number of parts has been slightly changed.

An electric motor 53 drives through the intermediary of gears 54, 55 and 56 the shaft of the lower roller 48 of the pressure roller pair 47, 48. Through mating gears 57, 58 the roller 47 is rotated in the opposite direction. The rotation of shaft 59 is transmitted through timing belt 60 to the intermediary shaft 61 which drives over the electro-magnetic clutch 62 the time delay mechanism 63 and through timing belts 65 and 66 and the magnetic clutches 67 and 68 also the aligning roller pairs 43, 44 and 45, 46. The various gears and belts are dimensioned so that the peripheral speeds of the different rollers are equal.

In the time delay mechanism 63 a gear 69 which may be coupled to the shaft 61 by the magnetic clutch 62, meshes with a gear 70 to which a zeroing disc 71 and a cam 72 controlling a stationary microswitch are mounted for joint rotation around a shaft 73. Rotatable shaft 73 carries a cam 74 controlling a microswitch 76 and a pointer knob 77 at its extremity which protrudes out of the lateral wall of the apparatus. A friction disc 78 is provided between the two cams 72 and 74 and a spring 79 biases cam 74 towards cam 72 so that upon rotation of the gear 70, both cams and the zeroing disc 71 will rotate together. A change in the longitudinal positioning of the sheets is obtained in briefly pressing the knob 77 when it is at rest and in turning it slightly whereby the cam 74 takes another angular position in respect of cam 72.

The time delay mechanism is also partly shown in FIG. 4, wherein for the sake of clarity some parts have been drawn on a different scale. The zeroing disc 71 cooperates with a pivotable lever 79 which is biased by a tension spring 80. The extremity of the lever carries a small rotatable roller 81 which snaps into a corresponding recess in the disc 71 and thereby accurately secures the inoperative position of the mechanism.

The electric circuit of the apparatus is shown in FIG. 5. It comprises a main switch 82 through which the motor 53 and a transformer 83 may be connected to an AC. supply at connections and 91. The rectified output tension of the transformer feeds the circuit comprising the pilot lamp 84 which is provided within the transparent cover of the main switch 82, the solenoids 68, 62 and 67 of the corresponding magnetic clutches, the relays 85 and 86 with correspondingly numbered contacts 85a, 85b, 85c and 86a, the pilot lamp 87 which is lit when the contact 88 controlled by a fioat in the reservoir 31 is closed thus warning there is short of processing liquid, and the change-over contacts 92 and 93 of the corresponding microswitches which are controlled by the fingers 50 and 52.

The different parts of the apparatus and the contacts of the electric circuit being in the inoperative position as shown in the figures, the operation of the apparatus is as follows.

Depending on the size of the sheets which must be treated, the operator adjusts the guides 25 and 28 and sets the time delay mechanism by turning knob 77 until the pointer thereof indicates on scale 95 the desired relative distance between the leading edges of both sheets. The main switch 82 is closed so that all driving rollers of the apparatus are continuously rotating. The operator swings the support plate 14 to an almost vertical position and puts the aluminium foil 13 with the image-receiving side turned upwardly, on plate 15. The foil is slid forwardly, the left edge gently urged against the guide 28, until the leading edge of the foil is gripped by the roller pair 45, 46. The sheet advance is arrested as the leading edge of the sheet slightly pushes away finger 50 so that the contact of microswitch 92 is changed-over and the circuit of solenoid 68 is interrupted. The operator swings the support plate 14 back and locates the image-wise exposed light-sensitive sheet 12 with the emulsion-side turned downwardly thereon. The sheet is pushed along the guide 25 until it is gripped by the roller pair 43, 44. The sheet advance is arrested as its leading edge actuates finger 52, so that the contact of microswitch 93 is changed-over and the circuit of solenoid 67 of the corresponding magnetic clutch is interrupted. The changing-over of contact 93 further causes the following operations to take place.

The relay 86 becomes energized and, over contact 85b, also the circuit of solenoid 62 of the corresponding clutch is closed. The energizing of relay 86 causes contact 86a to close, so that the circuit of solenoid 68 is closed again and the driving of the aluminium foil 13 is continued. The energizing of solenoid 62 starts the rotation of the time delay mechanism. As the shaft thereof has turned over a few degrees, the projection of cam 72 does no longer actuate the microswitch 75 so that the corresponding contact 75 becomes closed and makes the shaft effect just one revolution. After a short time, the projection of rotating cam 74 actuates the microswitch 76, so that over the corresponding contact thereof relay 85 is energized. Changed-over contact 85a closes the circuit of solenoid 67', so that the roller pair 43, 44 starts to rotate again and drives the sheet 12 through the apparatus in a well-determined longitudinal relationship with respect to sheet 13 which is being advanced by the roller pair 45, 46. The changed-over contacts 85b and 850 keep the circuit of the relay 85 closed until the two microswitches 92 and 93 resume again their initial rest position, which occurs when the trailing edges of both sheets have passed beyond the fingers 50 and 52. In the meantime the leading edges of the sheets were engaged by the rollers 47, 48 which press the sheets firmly to each other, thereby definitely securing the relative position of the sheets and starting also the diffusion transfer process. After the sheets have been pulled out of the apparatus by the rollers 47, 48 they are peeled from each other by the operator, and the imagereceiving side of the aluminium receiving sheet may be treated in a known way with a fixer composition to im prove the ink-receptive properties of the image parts and the ink-repellent properties of the non-image parts of the master obtained, and thereafter with a lacker to strengthen the mechanic properties of the image parts.

The returning to the initial position of the different parts of the electric circuit as soon as the trailing edges of the sheets have passed beyond the sensing means has the advantage that up from that moment a next pair of sheets may be located on the support plates and introduced into the apparatus. The adjustment knob 77 of the timedelay mechanism has reached already earlier its initial position since in the arrangement described, the shaft 73 makes about one revolution at two revolutions of the shafts of the roller pairs. Thus it is even possible to select another relative positioning of the sheets to be treated whilst the former sheets are still being processed in the apparatus,

The apparatus according to the present invention is not limited to the described embodiment.

In a modified arrangment, the pairs of rollers 43, 44 and 45, 46 were replaced by pairs of roller sections. Thus each roller was replaced by two roller sections which were mounted on a common shaft. The diameter of the roller sections was equal to that of the rollers 43 to 46 shown, their length amounted to about a quarter of the length thereof, and they were mounted at one quarter respectively at three quarters of the length of the shaft.

In the mentioned way, difficulties in connection with small angular displacements of the sheets in respect of the transport direction occurring when the leading edge of a sheet is not uniformly gripped by a pair of rollers, may be greatly reduced.

The processing zone may be arranged for application of the processing liquid in another Way to the sheets e.g. by means of a lick roller. Occasionally, a receiving sheet my follow a path which does not lead through the processing liquid so that said sheet is pressed against the lightsensitive sheet in dry condition.

The materials to be treated may be supplied in roll form and cut into sheets prior to their feeding into the apparatus.

The apparatus may comprise an exposure station for effecting the exposure of the light-sensitive material to the original.

The time delay mechanism may operate electrically rather than mechanically. In a known way, such electric circuit may comprise a resistor-capacitor circuit which controls a relay when charged or decharged to a given extent, and the time constant of which is adjustable.

Finally, by means of the outlet formed by an overflow pipe the adjustment of various levels of the processing liquid can be obtained. In this respect we refer to our co-pending Belgian patent application 48,330 for a Processing Device.

We claim:

1. In a copying apparatus for use in the silver complex diffusion transfer process and the like, comprising first guide means for guiding a first sheet along a determined path extending through a processing zone, second guide means for guiding a second sheet along a determined path spaced from said first sheet, and sheet-pressing and sheetdriving means arranged at the exit end of said zone for pressing said two sheets together and for removing said pressed sheets out of the apparatus, the improvement of variable positioning means for the leading edges of said sheets comprising an individually operable normally operating feeding means for each such sheet adjacent the ingress end of the corresponding guide means, a sensing means for each sheet disposed at a fixed locus between the corresponding feeding means and said processing zone and actuated by the arrival of the leading sheet edge at said locus, control means responsive to the actuation of the sensing means for the first sheet for stopping the feeding means for said first sheet, control mean responsive to the actuation of the sensing means for the second sheet for stopping the starting means for said second sheet, and simultaneously re-sta-rting the feed means for said first sheet and activating a variable time delay means effective after a predetermined variable period of delay to re-start the feed means for said second sheet, whereby said sheets are delivered to said processing zone with the leading edges thereof in precise controlled relation.

2. Apparatus according to claim 1 wherein said time delay means comprises a rotatable shaft which is coupled through a magnetic clutch to a continuously running electrlc motor, said magnetic clutch being energized by activation from said second sensing means, a first cam on said rotatable sheet operating a first microswitch to maintain said energization of said magnetic clutch for one complete revolution of said shaft, and a second cam adjustably mounted on said shaft in relation to said first cam and operating a second microswitch for re-starting the feeding means for said second sheet.

3. Apparatus according to claim 2, wherein the second cam controlling said second microswitch is angularly displaceable in respect of the first cam to vary the period of delay.

4. Apparatus according to claim 2, wherein said shaft comprises a first, hollow shaft portion carrying said first cam, and a second solid shaft portion passing axially through the first one, one end of said second shaft portion being accessible from the exterior of the apparatus and carrying a knob cooperating with a stationary dial to provide an indication of the distance between the leading edges of the sheets, as determined by the period of delay established by the relative positions of said earns, the opposite end of said second shaft portion carrying said cam, and a slip-clutch for coupling said first and second shaft portions.

5. Apparatus according to claim 4, wherein said rotatable shaft carries a third cam which is mounted jointly with said first cam, and which has a recess for receiving a spring-biased locking detent as the shaft reaches its inoperative position, to thereby accurately determine the angular position of the shaft in said inoperative position.

6. Apparatus according to claim 1 including feed guides for delivering said sheets to said feeding rollers comprising two support plates mounted in super-imposed relationship and each leading to the nip of a pair of said rollers,

the uppermost plate being mounted for movement away 20 from the other plate so as to facilitate the positioning of a sheet on said lower plate.

7. Apparatus according to claim 1, wherein said processing zone is formed by a body of liquid contained in a tray.

References Cited UNITED STATES PATENTS 2,883,929 4/1959 Eichenbaum et a1. 271-9 X 3,033,095 5/1962 Limberger 95-89 LAM X 3,241,485 3/1966 Hodges 95-89 M X 3,279,787 10/1966 Niccoli 271-57 X 3,455,229 7/1969 Frohock 95-94 FOREIGN PATENTS 656,554 1/1963 Canada 95 89 LAM 978,767 12/1964 Great Britain 95-89 LAM SAMUEL S. MATTHEWS, Primary Examiner R. P. GREINER, Assistant Examiner US. Cl. X.R. 95-89 R 

